Resins within the scope of formula I. are known. Nadimide terminated resins, that is resins of the formula: ##STR3## where n is an integer of 2 or more and R is an n-valent radical, are described in Scola et al, "Synthesis and Polymerization of Aliphatic Bisnadimides," J. Applied Polymer Science, 26 231-247 (1981); NASA Technical Memorandum 81976 (1981); NASA Technical Memorandum 83141; and St Clair et al "Polyimide Adhesives; Modified with ATBN and Silicone Elastomers," in Polymer Science and Technology I.F. Plenum 29 467-479 (1984). In these references the resins typically must be cured by a thermal reaction above the melt temperature under pressure and/or nitrogen to prevent the elimination of cyclopentadiene by reverse Diels-Alder reaction. Bismaleimide and bisnadimide compounds are also described as additives for free radically cured urethane acrylate formulations in G.B. Pat. No. 1546815 and U.S. Pat. No. 3,988,299.
In U.S. Pat. No. 4,560,768 polyimido-ester compounds of the formula: ##STR4## where R.sup.2 is an olefinically unsaturated group and R.sup.3 is: ##STR5## where n'=1-6, are described. These compounds may be used to improve thermal aging resistance of radically cured unsaturated resin-monomer formulations.
In U.S. Pat. No. 4,085,164 there are described thermo setting peroxide cured formulations of bisimide compounds, which reportedly may include nadimide compounds, and polyurethane elastomers.
Other resin compounds having groups of the structure shown in Formula I are isoimide resins described in U.S. Pat. No. 4,495,342 such as: ##STR6## where p is 0-30 these resins are also cured by thermal reaction.
While some of the foregoing described resin systems are formulations which will cure to solids at ambient temperatures, the norbornene groups will not crosslink into the system until the temperature is substantially elevated (eg. in excess of 200 degrees F.). Photocuring of these formulations is not practical because of the very strong UV absorbence of the imide groups.
Silicone imide resins and silyl norbornene anhydride compounds are described in U.S. Pat. Nos. 4,381,396; 4,472,565; and 4,404,350. These compounds are prepared by hydrosilation of the double bond in a nadimide or nadic anhydride compound.
Free radical cured thiol-ene systems have been known for a long time. The reaction involves addition of S--H-Groups across a olefinic or acetylenic double bond. Detailed discussion of the mechanism of this reaction and of the academic literature in this field may be found in Oae, ed., "Organic Chemistry of Sulfur", Plenum Press, New York, N.Y., pp. 131-187 (1977). Oswald et al reportedly disclosed photocrosslinkable compositions employing tetraallyl ester compounds and dithiols at the April 1965 ACS meeting in Detroit, Mich. See Oswald et al, Die Makromolekulare Chemie, 97, 258-266 (1966). Formulations of di-or poly-thiols and dienes or polyenes which are curable to solids by chemical or photolytic radical generators are also described in U.S. Pat. Nos. 2,767,156; 3,661,744; 3,240,844; 4,119,617; and 4,157,421. All of these prior art curable formulations have involved polythiol additions to double bonds in linear olefins or acetylene compounds.
Silicone polymers having alkyl thiol groups are disclosed in U.S. Pat. No. 4,289,867 and background references discussed therein. In U.S. Pat. No. 4,284,539 other silicones having linear and cyclic mercaptoalkyl groups are described as are the thiol-ene reactions of such materials with silicones having vinyl or silacylopentene groups. Peroxide cured compositions of vinyl terminated silicone and silicone or organic polythiols are described in U.S. Pat. No. 3,445,419.
Addition of thiols to six membered cyclic olefins such as cyclohexene is known but rate studies indicate that the rate of reaction to be extremely slow relative to allylic or vinylic compounds. See Oae, ed., "Organic Chemistry of Sulfur" Page 133. Thiol additions to norbornene have also been studied but apparently only for steric information. Oae Page 134-135. Addition of diethyl dithio phosphoric acid to dicyclopentadiene and norbornadiene is described in J. Org. Chem., 28 1262-68 (1963), however, this paper does not provide any relative correlation between reactivities of thiophosphate groups and organothio groups.
Crivello has described the preparation of polyimidothiothers by base catalyzed addition of dithiols to bismaleimide compounds. It is known, however, from the work of Oswald, cited above, that the maleimide bond is not subject to radical catalyzed thiol addition.
In U.S. Pat. No. 4,435,497 to Irving there are described polymerizable two component compositions in which the first component is a compound containing at least one each of (meth)acryloxy groups; allyl, methallyl, or 1-propentyl groups bonded through an oxygen or oxycarbonyl group to a aromatic or cycloaliphatic nucleus; and carboxylic acid groups. The second component is a polythiol. Irving teaches that the first component preferably does not include ethylenic unsaturation other than in the (meth)acryloxy, allyl, methallyl and 1-propentyl groups. However, the reference also does include partial esters of endomethylenetetrahydrophthalic acid with various (meth)acryloxy and allyl or methallyl substituted alcohols. Nothing in this reference, however, teaches or suggests that the norbornenyl structure which exists in such partial esters is capable of useful thiolene cross-linking reactions or that any of the three specifically required groups (i.e. acrylic, allylic, and carboxylic acid) could be dispensed with.
Thus, heretofore it has not been suggested that practical radically catalyzed thiolene crosslinkable systems can be prepared using compounds or resins having a plurality of norbornene groups as the 'ene compound.